i've never opened one of those, the Panasonic version has a potted control board and it is quite a pain to remove all the conformal coating without damage. i'm gonna guess that your board will be potted also.

The old version does 2 ground checks before allowing charging: one checks that the ground wire exists and provides a current flow path back for the Line; the other leaks a very low current thru the ground fault detection coil to prove that the GFCI circuit is functioning properly.